a. Field of Invention
The invention relates generally to vehicle structural design, and more particularly, to the structural design of a vehicle bumper system for improved impact deformation and resistance, particularly during bumper over-ride and under-ride conditions.
b. Description of Related Art
As is known in the art, automobile bumper systems are designed to absorb and distribute impact energy in a predetermined manner. While bumpers systems are generally designed to meet at equal vertical impact levels, in the event of bumper over-ride or under-ride (i.e. in the event of a car/truck collision), even a low speed impact can result in excessive vehicle damage. This is because typical bumper systems may include energy absorbers disposed at a height-wise central area of the bumper for providing impact resistance against a bumper presumably disposed at the same height, leaving the upper and lower ends of a bumper susceptible to over-ride or under-ride type collision which could result in vehicle damage.
U.S. Pat. No. 6,609,740 to Evans is exemplary of known bumper system designs. While the Evans design aims to consistently distribute the load of an impact, this design is nevertheless optimally suited for impact resistance against a bumper presumably disposed at the same height.
For example, Evans, as illustrated in FIGS. 4-6 thereof, provides for a bumper structure including bumper energy absorber (22) having top and bottom box-shaped sections (27) and (27′), which extend outwardly from beam (21) and have rearwardly extending nose section (28) in between. As illustrated in FIG. 6, kick walls (30, 31) press into the top and bottom mid-walls (23, 24), resulting in a consistent and controlled collapse of the energy absorber and tubes of the bumper beam.
Thus, as discussed above, whereas Evans attempts to provide consistent load distribution, in the event of an over-ride or under-ride condition, the respective upper or lower area of the bumper would bear almost all of the impact load, thus inhibiting the intended bumper deformation as illustrated in FIG. 6 of Evans, and resulting in excessive bumper damage. Likewise, the Evans design limits energy absorbing capability within the height of the bumper beam, and not beyond.
It is therefore desirable to provide a bumper system which provides a cost-effective means for minimizing bumper damage in the event of an over-ride or under-ride impact condition, and likewise providing consistent and predetermined bumper deformation. It is also desirable to provide a bumper system which is simple to design and manufacture, and which is readily adaptable to a variety of vehicle designs.